使用7zip sdk压缩文件，但无法使用winrar或7zip解压缩

Question

我从here下载了SDK 7zip。

然后我用这个代码文件压缩成7zip的：

private static void CompressFileLZMA(string inFile, string outFile) 
{ 
    Encoder coder = new SevenZip.Compression.LZMA.Encoder(); 

    using (FileStream input = new FileStream(inFile, FileMode.Open)) 
    using (FileStream output = new FileStream(outFile, FileMode.Create)) 
    { 
     coder.Code(input, output, -1, -1, null); 
     output.Flush(); 
    } 
} 

我试用过SDK版本9.20和9.22测试版的网站上。

压缩似乎正在从我的文件压缩：1.6 MB到239 KB。

但是，如果我使用WinRar或7zip来解压缩。存档文件不被认可他们的错误是一样

“未知归档文件或损坏的文件”

任何想法呢？

Answer 1

您可以尝试使用7zSharp wrapper或至少分析包装代码如何完成所有工作。

代码压缩文件（从7zSharp拍摄）：

public void EncodeSingleFile(string inFile, string outFile) 
    { 
    using (FileStream inStream = new FileStream(inFile, FileMode.Open, FileAccess.Read)) 
    { 
     using (FileStream outStream = new FileStream(outFile, FileMode.OpenOrCreate, FileAccess.Write)) 
     { 
      EncodeSingleFile(inStream, outStream); 
     } 
    } 
    } 

    public void EncodeSingleFile(FileStream inStream, FileStream outStream) 
    { 
    bool eos = false; 
    Int32 dictionary = 1 << 21; 
    Int32 posStateBits = 2; 
    Int32 litContextBits = 3; // for normal files 
    // UInt32 litContextBits = 0; // for 32-bit data 
    Int32 litPosBits = 0; 
    // UInt32 litPosBits = 2; // for 32-bit data 
    Int32 algorithm = 2; 
    Int32 numFastBytes = 128; 
    string mf = "bt4"; 

    propIDs = new CoderPropID[] 
     { 
      CoderPropID.DictionarySize, 
      CoderPropID.PosStateBits, 
      CoderPropID.LitContextBits, 
      CoderPropID.LitPosBits, 
      CoderPropID.Algorithm, 
      CoderPropID.NumFastBytes, 
      CoderPropID.MatchFinder, 
      CoderPropID.EndMarker 
     }; 
    properties = new object[] 
     { 
      dictionary, 
      posStateBits, 
      litContextBits, 
      litPosBits, 
      algorithm, 
      numFastBytes, 
      mf, 
      eos 
     }; 

    Encoder encoder = new Encoder(); 
    encoder.SetCoderProperties(propIDs, properties); 
    encoder.WriteCoderProperties(outStream); 
    Int64 fileSize = inStream.Length; 
    for (int i = 0; i < 8; i++) 
    { 
     outStream.WriteByte((Byte) (fileSize >> (8*i))); 
    } 
    encoder.Code(inStream, outStream, -1, -1, null); 
    } 

Answer 2

它在Stream级别上运行的事实表明它只是在执行lzm压缩/解压缩逻辑，而不是构建实际的归档文件（归档文件将是.zip或.7z文件）。类似于使用GZipStream或DeflateStream - 它不会生成档案。 WinRar和7zip等工具可用于档案。

我期望在该API中有另一种类型，它实际上会生成一个档案，但是会期望更多的信息，例如文件名（它几乎肯定会接受多个文件/流）。

Answer 3

您是否看过SDK附带的示例项目？它位于CS\7zip\Compress\LzmaAlone\文件夹中，它包含一个文件LmzaAlone.cs，它有一些编码文件的内容。它做了一些类似这样的写入了压缩数据之前：

CoderPropID[] propIDs = 
{ 
    CoderPropID.DictionarySize, 
    CoderPropID.PosStateBits, 
    CoderPropID.LitContextBits, 
    CoderPropID.LitPosBits, 
    CoderPropID.Algorithm, 
    CoderPropID.NumFastBytes, 
    CoderPropID.MatchFinder, 
    CoderPropID.EndMarker 
}; 
object[] properties = 
{ 
    (Int32)(dictionary), 
    (Int32)(posStateBits), 
    (Int32)(litContextBits), 
    (Int32)(litPosBits), 
    (Int32)(algorithm), 
    (Int32)(numFastBytes), 
    mf, 
    eos 
}; 

Compression.LZMA.Encoder encoder = new Compression.LZMA.Encoder(); 
encoder.SetCoderProperties(propIDs, properties); 
encoder.WriteCoderProperties(outStream); 
if (trainStream != null) 
{ 
    CDoubleStream doubleStream = new CDoubleStream(); 
    doubleStream.s1 = trainStream; 
    doubleStream.s2 = inStream; 
    doubleStream.fileIndex = 0; 
    inStream = doubleStream; 
    long trainFileSize = trainStream.Length; 
    doubleStream.skipSize = 0; 
    if (trainFileSize > dictionary) 
     doubleStream.skipSize = trainFileSize - dictionary; 
    trainStream.Seek(doubleStream.skipSize, SeekOrigin.Begin); 
    encoder.SetTrainSize((uint)(trainFileSize - doubleStream.skipSize)); 
} 
// only now does it write out the compressed data: 
encoder.Code(inStream, outStream, -1, -1, null); 

，所以它看起来像你需要先写了几个文件头给有关即将到来的压缩数据的细节。

如果您下载了source for 7Zip，那么您会发现在doc文件夹中有一个文件7zFormat.txt，其中包含对7个zip文件格式的描述。这可能会帮助您创建有效的档案。